Nick Mader of Freemont Brewing Co. carried out a series of fermentation trials using Saccharomyces cerevisiae BSI 565, a highly attenuative Saison strain and BSI drie a Brettanomyces bruxellensis strain isolated from a lambic beer.

They were cultured in a wort of 13.4° Plato (1.054) and 5.2 pH which was oxygenated to 10ppm O2

Five trials were each carried out in triplicate. The cultures used five trials were:

Pure Sacch.

75% Sacch. /25% Brett.

50% Sacch. /50% Brett.

25% Sacch. /75% Brett

Pure Brett.

Only 2.5% difference in apparent attenuation was found in the mixed cultures, so mixed culture fermentations had similar attenuation to pure Sacch.

Pure Brett. had77% apparent attenuation (3.1°P FG)

Fermentations were carried out at 20°C

Laboratory (GC) and sensory analysis was carried out.

Esters:

Ethyl acetate (in high concentration solventy taste, in medium conc. fruity). Highest conc. in pure Sacch. Decreased at first with Brett. in mix and then increased as Brett. conc. went up, so at 75% Brett. it's almost as high as pure Sacch. Ethyl butyrate had negative linear relationship with % of Brett.

Pure culture fermentations had compounds in high concentrations but fewer of them. Mixed fermentations had more compounds in medium concentrations which gave a more complex taste.

I thought that last point about mixed culture fermentations really interesting: less intensity but more variety in flavour compounds giving a more complex taste. It looks obvious now, but it was useful to hear it stated.